This is an investigator-initiated, multicenter, randomized, crossover design study to compare the therapeutic effectiveness of split-mixed BID insulin using human regular and ultralente insulin or pork regular and NPH. All subjects (20 from each of 5 centers; 100 in total) must have IDDM, be 4-11 years old, and be prepubertal. Each will be treated for six months with each regimen in randomized sequence. Glycemic control and hypoglycemia rates will be assessed.